<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Title</title>
    <style>
        * {
            padding: 0;
            margin: 0;
        }

        #root {
            width: 375px;
            height: 100px;
            background: red;
        }
        #one{
            width: 50%;
            height:100px;
            background: green;
        }
        #two{
            width:187.5px;
            height: 100px;
            background: pink;
        }
    </style>
</head>
<body>
<div id="root"></div>
<div id="one"></div>
<div id="two"></div>
</body>
<script >
    console.log(window.devicePixelRatio)
</script>
</html>